A storage system can manage a plurality of logical storage devices of which storage areas are a part of storage areas of a plurality of storage devices. In this storage system, logical storage devices can be provided to a host computer so that the host computer can recognize them, and can execute the data input/output processing for the logical storage devices.
In the storage system, if an input/output request is received from the host computer, a microprocessor installed in the storage system controls the input/output processing, such as data write processing to the storage device or data read processing from the storage device according to the input/output request.
Some storage systems have a plurality of microprocessors for executing the input/output processing to/from the storage devices. In such a storage system, a microprocessor, which is in-charge of the input/output processing to/from each logical storage devices, is predetermined, and if an input/output request is received from the host computer, the microprocessor, which is in-charge of the input/output processing for the logical storage device indicated by this input/output request, performs input/output processing based on this input/output request (see Japanese Patent Application Laid-Open No. 2005-301802, for example).
According to the technic disclosed in Japanese Patent Application Laid-Open No. 2005-301802, a microprocessor which performs input/output processing can be set according to the logical storage device indicated by the input/output request, so load on the microprocessors can be balanced.
However, in order to set a microprocessor which is in-charge of a logical storage device, the administrator of the storage system must define the logical storage device and the microprocessor which is in-charge of this logical storage device when the logical storage device is created, and this defining is difficult and takes time.
Also when a logical storage device is created, even if a microprocessor to be in-charge of the logical storage device is determined considering the load of the microprocessor, the load of the microprocessor may not be balanced appropriately as originally designed when the logical storage device is actually used. In the case of a conventional storage device, a way of changing the charge of the logical storage device is not considered.